1. Field of the Invention
The present invention is directed to a method for colour correction for images.
2. Description of the Background Art
In the prior art, many attempts have concentrated on the correction of digital colour data belonging to images of any kind. In particular, scanned negative or positive films have been transformed to digital data and have been directed to several different processes or methods to correct the colours of these image colour data. In addition, many pictures taken by consumers by means of digital still cameras also suffer from colour deviations which can also be based on the application of particular colour corrections accomplished by the software of the cameras themselves. It is known that photofinishing laboratories printing photos on the basis of the digital image data taken by still cameras have to manually correct the colours of up to 50% of the images before printing out these images. Otherwise, the colour quality of these prints would not be deemed to be sufficient by the customer. Accordingly, the cost of printing out in particular images taken by digital still cameras incurs considerably higher costs because the colour correction has to be accomplished manually.
Many colour correction algorithms are available. However, each of these colour correction algorithms or processes only provides satisfactory results for a very limited range of images. Furthermore, the known colour correction processes are based on the assumption that calibrated systems are used to take the photographs, whereas, digital still cameras, however, already implement an automatic correction or adaptation of the colour data of an image. Thus, since typical digital still cameras already transform colour image data into a particular colour space in the processor of the digital still camera, the known colour correction processes are not able to work with colour image data recorded by typical digital still cameras.
As outlined above, each of the usual colour correction processes is only applicable with acceptable results to certain types of images with certain features. On the other hand, the same colour correction processes render bad results for other types of images having other characteristics. Therefore, it is not possible to use the known colour correction processes for all types of images. Furthermore, as far as manual colour correction is concerned, it is not possible to implement this without the interaction of an educated and experienced, and thus very expensive operator.